dk1
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Drives me bonkers. They are being changed on 13/14 to allow more trains to draw up behind.
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Abellio Greater Anglia Class 755s (Regional Trains)
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Railperf
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I'm confused by the difference between the plated unit and individual vehicle weights!
The plate on a 755/4 says the complete unit weighs 163.4t.
But the individual weights of each vehicle add up to no more than 112.2 tons? Either somebody cannot add up or there is an explanation as to why they figures don't reconcile. The vehicle weights as plated are: DMS127.3t, PTS 13.8t, PP 27.9t, PTSW 16t, DMS2 27.2t.
Can anyone work that out? With 3,500 electric horsepower on tap - and 163 tons, that's a phenomenal 22hp/ton. But if the unit weight is only 112 tons, then that's closer to 30hp/ton - TGV levels of power on a low geared 100mph unit - Absolutely bonkers!!!
The plate on a 755/4 says the complete unit weighs 163.4t.
But the individual weights of each vehicle add up to no more than 112.2 tons? Either somebody cannot add up or there is an explanation as to why they figures don't reconcile. The vehicle weights as plated are: DMS127.3t, PTS 13.8t, PP 27.9t, PTSW 16t, DMS2 27.2t.
Can anyone work that out? With 3,500 electric horsepower on tap - and 163 tons, that's a phenomenal 22hp/ton. But if the unit weight is only 112 tons, then that's closer to 30hp/ton - TGV levels of power on a low geared 100mph unit - Absolutely bonkers!!!
ac6000cw
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Could those individual vehicle weights be excluding the (shared) bogie weights i.e. total set weight = vehicle weights plus bogie weights?
delticdave
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How does a 755/4 compare with other UK dmu's in it's power to weight ratio/(1920 kW & ??? tonnes.)?
I ask 'cos most of their in service mileage won't be under the wires.
Railperf
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It had crossed my mind. I just wanted to see if anyone knew definitively. It certainly makes sense!
Railperf
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Stadler quote the installed diesel power as 1920kW which equals 2574hp and 15.8hp/ton.
The most powerful older DMU's seems be Class 222's. A 5-car unit has 3,750hp and weighs 249t, so power to weight ration of 15hp/t.
But the 222 is geared for 125mph, while the 755 is probably only geared for 100mph.
If you are looking at what the 755;s are replacing - A 2-car Class 170 has 844hp for a weight of 88.4 tons - so 9.54hp/ton.
And a 2-car Class 156 unit has only 570hp for 74.7 t - so 7.63hp/t.
So a 755 has double the power of a 156, and a third more power than a 170!
If we base the Class 755 power at rail figure to be 80% of the installed 2,574 diesel hp, we get 2059hp which is around 12.6hp/t.
Comparing to electric units - the Greater Anglia Class 360s are around 15.8hp/ton, while a Class 321 has only around 10.3hp/ton.
No surprise then that a 755 out accelerates the 321 but is slightly behind a 360 from 0 to 90mph based on real life recordings.
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delticdave
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Thanks for all of the above info, 'tis appreciated. I'm guessing that the 755/3's with 960 kW / 1287hp, but with 1 car less could at least keep to the existing timings on the branches. They might be ideal (as a pair of 3-car sets)for the through London - Lowestoft workings as (AFAIK) the East Suffolk route has some severe speed restrictions, + when under the wires they would have the same power at the rail as a 12-car 745.........
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Railperf
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By my reckoning the 755/3 will be 9.4hp/ton installed power - so on a par with a 170 and a bit more power than a 156.
But if only 80% of the diesel power is being converted to electrical power and reaching the rail - it starts to look a feeble 7.5hp/t. But then when you apply the same formula to the 170 and 156, their power to ratios also drop accordingly. So still reasonably on a par with a 170, but having the superior AC electric traction drive and modern traction electronics.
I'm not sure about the wisdom of clogging up the main line with a pair of 3-car units. A pair of 4-car's would make far more sense. Reminds me of the days when 'One' railway sent a 3-car 170 down to London once an hour. What a waste of a train path. And the 170's were frequently full and standing - especially in the peaks.
Railperf
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getting back to reliability - there don't seem to be many staff - drivers / conductors etc that have much good to say about the 755's and the biggest complaint is that they keep 'breaking down'. Door issues and engine issues seem to be a problem. Apparently if the engines get too hot they just shut straight down and there seems to be a problem restarting them. Does it sound a similar story?!!
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rdlover777
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i dont understand why all the failures and breakdowns only started to occur once they were in service, during testing they seemed to work flawlessly
grumblingalong
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Deleted.
EE Andy b1
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Real World testing!
Railperf
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Yes i cannot imagine the driving vehicles being twice as heavy as the intermediate vehicles. So the vehicle weight for the driving vehicles clearly includes the weight of the end powered bogie.
Whereas the intermediate vehicles mounted on articulated bogies are plated as half the weight of the driving vehicles. The difference of vehicle weights to unit weight then is around 50t which divided between the 4 articulated bogies is appx 12.8t per bogie. Add the weight of two 'half' bogies to the intermediate vehicle and it now weighs the ssme as the end vehicles.
Interestingly that gives us a clue as the the axle weight for the power pack. Assuming the majority of the power pack weight is loaded onto the its side of the articulated bogie you have around 14 tons of actual weight and then 6 tons for the half' bogie. So 20 tons per axle - which sounds a lot.
On the intermediate vehicle that would be around 7 tons of body weight plus 6ish tons for the bogie / wheelset. So only 13 tons on that axle.
Or is the weight supported in such a way that the weight is evenly distributed across the bogie? If not, the inner axle wheelset closest to the power pack is taking a lot more load. Would that create uneven wear?
I've just passed Cambridge station and seen 755 410 in platform 5, presumably waiting to form the 1009 to Norwich. This service hasn't previously been a 755 (normally it's the 1109 that is) - so there's either something unusual today or the diagrams have been changed.
ac6000cw
Established Member
I think it would have to be.
If the points where the two bodies transfer their weight to the bogie are close together (or even better, concentric), there will be natural distribution of the weight anyway between the axles. Simplistically, a normal 2-axle bogie is a bit like an upside-down see-saw - the vehicle weight pushes down on the centre and the bogie frame will distribute that weight equally to both axles via the primary suspension.
delticdave
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They will be concentric, somewhere in the house are drawings for the Gresley articulated bogies, which used domed castings one the centre of the bogie & one each on each coach. The set-up allowed rotating & twisting movement, & from my quint-art memories a very acceptable ride. (I'm old enough to remember the last years of steam on the Jazz.)
ac6000cw
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I think a while back there were photographs published of at least part of the FLIRT body-bogie connection arrangement (I think Stadler/GA organised a trip for journalists/stakeholders to the factory in Switzerland, so several magazines had coverage of the visit).
EDIT: not the one I was thinking of, but found this on Wikimedia Commons:
The caption says: "Joint of a Stadler FLIRT, Belarus version (broad gauge). The joint is taken apart, and the bogie is missing (it fits onto the spike at the bottom)."
So I assume (when moved together and joined) the horizontal shaft on the right should sit in the channel on the left. It looks like the shaft can move around in its housing (like a ball joint), to accommodate the relative movements of the cars - there seems to be grease in that area.
EDIT: not the one I was thinking of, but found this on Wikimedia Commons:
The caption says: "Joint of a Stadler FLIRT, Belarus version (broad gauge). The joint is taken apart, and the bogie is missing (it fits onto the spike at the bottom)."
So I assume (when moved together and joined) the horizontal shaft on the right should sit in the channel on the left. It looks like the shaft can move around in its housing (like a ball joint), to accommodate the relative movements of the cars - there seems to be grease in that area.
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Railperf
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Had a chance to analyse Class 755 performance vs a Class 170 run between Norwich and Cambridge.
The 755 beat the 170 timings by almost a minute on most station to station sections - Ely to Brandon 1 min 33sec quicker, Brandon to Thetford 1 min 10 sec quicker, and Attleborough to Wymondham 51 sec quicker.
Similar time improvement going back to Cambridge - Norwich to Wymondham 53 sec quicker, Wymondham to Attleborough 57 sec quicker, Thetford to Brandon 53 sec quicker, Brandon to Lakenheath 44 sec quicker, Lakenheath to Ely 58 sec quicker.
The 170 appeared to have been driven hard to try and keep to time in both directions. But the 755 comfortably outpaces it.
it will be a shame if this isn't reflected in reduced journey times once the whole fleet is introduced due to dwell times being longer! And of course operational constraints at Norwich, Ely and Cambridge!
In terms of fuel usage - the 755 only needs to be on full power for around 2 mins to reach 90mph whereas the 170's are running at full pelt for 5 or 6 minutes to reach that speed. So i would be surprised if the 755's used that much extra fuel. And proportionally there is slightly less weight for a 4-car (5-car if you include the PP) the the 170 too - and I am guessing less rolling resistance!
The 755 beat the 170 timings by almost a minute on most station to station sections - Ely to Brandon 1 min 33sec quicker, Brandon to Thetford 1 min 10 sec quicker, and Attleborough to Wymondham 51 sec quicker.
Similar time improvement going back to Cambridge - Norwich to Wymondham 53 sec quicker, Wymondham to Attleborough 57 sec quicker, Thetford to Brandon 53 sec quicker, Brandon to Lakenheath 44 sec quicker, Lakenheath to Ely 58 sec quicker.
The 170 appeared to have been driven hard to try and keep to time in both directions. But the 755 comfortably outpaces it.
it will be a shame if this isn't reflected in reduced journey times once the whole fleet is introduced due to dwell times being longer! And of course operational constraints at Norwich, Ely and Cambridge!
In terms of fuel usage - the 755 only needs to be on full power for around 2 mins to reach 90mph whereas the 170's are running at full pelt for 5 or 6 minutes to reach that speed. So i would be surprised if the 755's used that much extra fuel. And proportionally there is slightly less weight for a 4-car (5-car if you include the PP) the the 170 too - and I am guessing less rolling resistance!
306024
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You will have to be patient before seeing any reduction of journey times. The lead times for timetable planning are considerable, and neither NR or GA are going to commit to anything without sufficient proven data. Far better to start with to bag the performance improvements first and then look at journey opportunities later when all staff are used to the fleet and they are fully bedded in.
Railperf
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of course. We are not expecting anything tomorrow.
My point was it will be a shame if the performance of these trains isn't exploited in years to come with faster journey times due to operational constraints - paths at the junctions at Ely / Norwich or that longer dwell times will eat up any time savings gained.
This seems to be a train that can start to provide almost Intercity style performance on the regional routes - if money is spent on signalling and track to increase the route speed limits.
dk1
Veteran Member
Signalling across the Norwich/Ely route was all geared up for 90mph when resignalled a few years ago. Sadly though this was not a project that included this & there are even follies such as reductions of 10mph briefly for signal sightings issues on signals that are no longer there. Drivers have this monitored when downloaded reguardless that it no longer serves a purpose.
For the time being all schedules are made to accommodate class 156 stand ins so they maintain time but going forward there should be a few minutes shaved off. I'm not holding out much hope for Line speed improvements however.
For the time being all schedules are made to accommodate class 156 stand ins so they maintain time but going forward there should be a few minutes shaved off. I'm not holding out much hope for Line speed improvements however.
Railperf
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That is ridiculous!! So much for spending millions on new trains and then not dealing with these minor operational issues. I cannot believe it. Which location is that? Am I right in thinking just North of Wymondham - where there is a very slow start and crawl before powering up to Norwich?
Operationally, Trwose junction is a pinch point as is the swing bridge. Also the fact that Platforms 4,5 and 6 all seem to be on the same lead in- which means there is no chance for parallel moves.
I was stuck on a 755 sitting by Crown Point having arrived very early but couldn't get into a Vacant platform - probably because the route was set out of 4 or 6.
Again, the Yarmouth route is crying out for some improvements. The turnout speeds at Acle and at Yarmouth itself should be at least 40mph - rather than 20 and 15mph. The line is so straight it surely is suitable for at least 75mph and even 90mph. No wonder passengers would rather use the car.
dk1
Veteran Member
No chance of any upgrades on the Wherry lines. Lowestofts turnouts will be 40 instead of 10, Brundall to the Acle branch is 25 rather than 15 & it's now 40up/60dn through Reedham rather than 20/15 but that's your lot.
Wymondham down is for stopping trains due to Browick AHBs and the now lost possibility of a extra crossover (Attleborough down is similar for Spronces AHBs) . That won't change either in the medium to long term. Approaching Brandon on the up it goes 90-85-90 for no reason anymore and Harling Road down is 90-80-90 too. It's been like that for over 7 years.
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Railperf
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where are you sitting in the train?
I was in the second coach, but at the end furthest from the engines. You can hear them a little bit but it’s hugely better than a Turbostar, with no vibration. Reminds me of the 800s in diesel mode.
Railperf
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Try sitting as close to the engines next time and tell us what you think. And then as close as you can to the front or rear. I would be interested to hear how you compare the 3 seating positions in terms of noise.